Light, photometry and illumination : a thoroughly rev. ed. of ''Electrical illuminating engineering'' (1912)
Barrows, William Edward, 1878-1960 · New York ; London : McGraw-Hill Book Co. · leaf 97
is attached to the sleeves. Theother end of the lever may be placed above a scale calibrated toindicate by the position of the lever the value of the openings inthe disk. With this arrangement the intensity can only bevaried through a range of about 50 per cent. The minimum speed of rotation is… … 0.1 1.0 Meter Candles 1000 Fig. 25.—Frequency at which flicker becomes perceptible for difierentintensities of illumination. (Sectored disk.) alternating current supplied to the illuminant. Investigationsof the critical speed of the disk were conducted by Ferry* andPorter^ where light of known…
Light · Photometry · Electric lighting
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